Open ocean or ‘pelagic’ habitat covers most of the planet and is the largest habitat type on Earth. Extending from the sea surface to near the seafloor, pelagic habitats support a vast diversity of species—from tiny plankton to blue whales—that depend on the ocean for food, movement, communication, and other essential functions. Many species that are important to open ocean ecosystems, such as humpback whales and albatross, are seasonal visitors to the Olympic Coast, traveling great distances each year to feast on the productivity of this special place during the upwelling season. Continue reading from National Oceanic and Atmospheric Administration
In fact, the open ocean ecosystem is so large it has been divided into five distinct zones according to depth. Each zone is characterised by different physical properties, including light availability, pressure and temperature.
The Five Zones of the open ocean:
1. The Epipelagic or Sunlight Zone is the area from the surface to 200m deep. Light is still able to penetrate here so photosynthesis can take place.
2. The Mesopelagic or Twilight Zone is the area between 200-1000m deep. Here light starts to become very limited and there is less oxygen available to the organisms that live here.
3.The Bathypelagic or Midnight Zone lies between 1000-4000m deep. Light is no longer able to penetrate to these depths leaving this region of the ocean in complete darkness.
4. The Abyssopelagic Zone extends from 4000-6000m deep, and is commonly known as The Abyss due to a lack of life found in the water column at these great depths.
5. The Hadopelagic Zone is characterised by deep sea canyons and trenches exceeding depths of 6000m. This includes the famous Mariana Trench which contains the deepest known point on the Earth’s surface, the Challenger Deep, with a depth of 11,034 metres. Continue reading from The Marine Diaries
The open ocean provides us with many benefits in terms of ecosystem services. The ocean is critical in regulating the temperature of the earth by absorbing heat and regulating air temperature. Phytoplankton in the water column also produces an enormous amount of oxygen while capturing (sequestering) and storing carbon dioxide. Continue reading from MzanSea
